This study aims to develop and validate a semi-quantitative FFQ specifically designed to assess dietary intake among Turkish adults (19–64 years), based on the Türkiye Dietary Guideline (TDG-SFFQ). The primary goal is to evaluate the validity and reproducibility of the TDG-SFFQ to ensure it accurately captures habitual dietary patterns in the target population.

The TDG-SFFQ was administered through face-to-face interviews. Validity was assessed by comparing it with a 24-h dietary recall, while reliability was evaluated using a test-retest method after 4 weeks with fifty-six participants in Ankara, Türkiye. Daily intake means for energy, macronutrients and micronutrients obtained from both the TDG-SFFQ and 24-h dietary recall were calculated. Concordance between the two methods was analysed using the Pearson correlation coefficient and Bland–Altman plots.

Participants with adequate communication skills were recruited through digital announcements on social media and professional networks, followed by a snowball sampling method to expand the study reach. All eligibility screenings and subsequent data collection were conducted through face-to-face interviews.

The study group consisted of adults (n 420).

The agreement between the two methods demonstrated a statistically moderate or higher correlation for energy and macronutrients. Graphical representations for micronutrients also clustered around the mean, remaining within the 95 % CI. The reliability assessment of the TDG-SFFQ revealed strong linear correlations for energy and nutrients (p < 0·05), with intraclass correlation coefficients exceeding 0·666.

In summary, the TDG-SFFQ is a potentially valid and reliable tool for evaluating dietary intake in the Turkish adult population.